This is for 4.0L engine only:
A couple of days ago I learned something while working on my WJ (replacing the water pump). I have some great tips & tricks for you:
1) the service manual says that you can replace the water pump without having to remove the radiator and other parts. Well, it's possible to do that but I hate to bend over and trying to unscrew the water pump bolts (my back often hurts while bending over). So, I went a different route: remove the front bumper/grille, inside "grille" (a black skeleton-like grille behind the grille), headlights, cross-brace and finally...the radiator. Of course, I had to drain the coolant first, in a clean 5 gallon container so I can reuse it. Removing the radiator is pretty easy. After the radiator is removed, you can replace the water pump pretty easy!!!
2) When you are trying to remove the viscous fan, you'll notice the water pump pulley (attached to the viscous fan) is impossible to hold while trying to loosen the fan clutch. I bought a special tool, it is called "Locking Chain Clamp." It's available at Harbor Freight for $10 (you can get it for less if you can find a 20% or 25% coupon). See the picture. It's the EASIEST way to "hold" the water pump pulley with that tool while loosen the fan clutch nut. When you stand in the front of your Jeep, you need to hold the locking chain clamp with your right hand while pulling the fan clutch wrench with your left hand. Pull the wrench to left (to unscrew the fan clutch nut from the water pump). The nut will become loosen pretty easy. No need to hit the nut with a hammer or anything like that.
3) I bought a brand new Mopar water pump for my Jeep. Yes, some people out there would tell me "but it came with plastic impleller". That is true, it did come with a plastic impleller. Keep in mind, the Mopar water pump is expected to last about 45,000 - 50,000 miles (the first water pump I had it in my Jeep). The non-Mopar water pump was installed in my Jeep and it lasted only 15,000 miles (the second pump). It was installed by an independent shop. For the 3rd water pump, I've decided to do that by myself, I went with Mopar water pump. It'll give me a peace of mind knowing that I won't have any trouble with it for the next 45,000 miles or so. I've considered Flowkooler water pump, but I found out that it is actually a GMP brand water pump (cheap brand). FlowKooler installed a metal disc (riveted) to GMP-brand water pump impeller. Well, I do believe that Mopar parts are better made parts over cheap non-Mopar brand parts. You can't go wrong with any Mopar parts. For example, I've researched on the JeepForum, some people went with non-Mopar radiator and they were having some issues with overheating. Non-Mopar radiator have smaller (or thinner) cores. Mopar radiator have the right size of cores and it'll help to keep the coolant temperature more stable and a tick (or two) under 210 degrees (my Jeep runs at 205-208 degrees). Non-Mopar thermostat isn't a good to have for your Jeep. Go with Mopar brand thermostat and you won't have any trouble with your Jeep's coolant system.
4) The 4.0L engine coolant system doesn't have a bleeder valve to let the air gap out of its system. The best way is to squeeze the top radiator hose several times while the radiator filler neck is not covered with a cap. You will see air coming out while squeezing the hose. Do that several times while refilling the coolant system with 50/50 mix of antifreeze and distilled water. After you use your Jeep a several times in the next couple days, you need to check your coolant system again. When the engine is cold, open the radiator cap and you will see no coolant in there, you need to add more 50/50 antifreeze-distilled water in there, squeeze the top hose a few times and you'll be surprised that there are some air still trapped in the system.
5. While changing the water pump, ALWAYS replace the thermostat!!! Go with Mopar-brand thermostat. Also, it's a good idea to replace the radiator cap as well.
6. I was going to reuse the water pump bolts. One of the bolts head snapped while tighting the bolt. I immediately removed the water pump and the head-less bolt is there, screwed in the engine block. I was relieved to see that it is about 1/4 inch outside (not flushed or snapped INSIDE of the hole). I was able to remove it with a vise grip tool (no need to go with an extraction tool). I learned a lesson by not using the bolts. I went to the local auto parts store and bought brand new bolts. Here's my advice, you should buy brand new bolts for your new water pump. The old bolts are old, beaten-up, stressed by hot-cold engine temperature and probably stretched out. The water pump uses five bolts, one of them is a little longer (about 1 3/4 inches long). I couldn't find 1 3/4 inches long bolt, so I had to use the old bolt. The other four bolts are 1 1/4 inches, they can be found at the auto parts store. I use Dorman brand 5/16"-18 x 1 1/4" Hex Head Cap Screws. You should also include 5/16" washers. I had to go real easy on an old bolt. The bolts should be tighted at 30 ft/lbs.
Hope it helps!
A couple of days ago I learned something while working on my WJ (replacing the water pump). I have some great tips & tricks for you:
1) the service manual says that you can replace the water pump without having to remove the radiator and other parts. Well, it's possible to do that but I hate to bend over and trying to unscrew the water pump bolts (my back often hurts while bending over). So, I went a different route: remove the front bumper/grille, inside "grille" (a black skeleton-like grille behind the grille), headlights, cross-brace and finally...the radiator. Of course, I had to drain the coolant first, in a clean 5 gallon container so I can reuse it. Removing the radiator is pretty easy. After the radiator is removed, you can replace the water pump pretty easy!!!
2) When you are trying to remove the viscous fan, you'll notice the water pump pulley (attached to the viscous fan) is impossible to hold while trying to loosen the fan clutch. I bought a special tool, it is called "Locking Chain Clamp." It's available at Harbor Freight for $10 (you can get it for less if you can find a 20% or 25% coupon). See the picture. It's the EASIEST way to "hold" the water pump pulley with that tool while loosen the fan clutch nut. When you stand in the front of your Jeep, you need to hold the locking chain clamp with your right hand while pulling the fan clutch wrench with your left hand. Pull the wrench to left (to unscrew the fan clutch nut from the water pump). The nut will become loosen pretty easy. No need to hit the nut with a hammer or anything like that.
3) I bought a brand new Mopar water pump for my Jeep. Yes, some people out there would tell me "but it came with plastic impleller". That is true, it did come with a plastic impleller. Keep in mind, the Mopar water pump is expected to last about 45,000 - 50,000 miles (the first water pump I had it in my Jeep). The non-Mopar water pump was installed in my Jeep and it lasted only 15,000 miles (the second pump). It was installed by an independent shop. For the 3rd water pump, I've decided to do that by myself, I went with Mopar water pump. It'll give me a peace of mind knowing that I won't have any trouble with it for the next 45,000 miles or so. I've considered Flowkooler water pump, but I found out that it is actually a GMP brand water pump (cheap brand). FlowKooler installed a metal disc (riveted) to GMP-brand water pump impeller. Well, I do believe that Mopar parts are better made parts over cheap non-Mopar brand parts. You can't go wrong with any Mopar parts. For example, I've researched on the JeepForum, some people went with non-Mopar radiator and they were having some issues with overheating. Non-Mopar radiator have smaller (or thinner) cores. Mopar radiator have the right size of cores and it'll help to keep the coolant temperature more stable and a tick (or two) under 210 degrees (my Jeep runs at 205-208 degrees). Non-Mopar thermostat isn't a good to have for your Jeep. Go with Mopar brand thermostat and you won't have any trouble with your Jeep's coolant system.
4) The 4.0L engine coolant system doesn't have a bleeder valve to let the air gap out of its system. The best way is to squeeze the top radiator hose several times while the radiator filler neck is not covered with a cap. You will see air coming out while squeezing the hose. Do that several times while refilling the coolant system with 50/50 mix of antifreeze and distilled water. After you use your Jeep a several times in the next couple days, you need to check your coolant system again. When the engine is cold, open the radiator cap and you will see no coolant in there, you need to add more 50/50 antifreeze-distilled water in there, squeeze the top hose a few times and you'll be surprised that there are some air still trapped in the system.
5. While changing the water pump, ALWAYS replace the thermostat!!! Go with Mopar-brand thermostat. Also, it's a good idea to replace the radiator cap as well.
6. I was going to reuse the water pump bolts. One of the bolts head snapped while tighting the bolt. I immediately removed the water pump and the head-less bolt is there, screwed in the engine block. I was relieved to see that it is about 1/4 inch outside (not flushed or snapped INSIDE of the hole). I was able to remove it with a vise grip tool (no need to go with an extraction tool). I learned a lesson by not using the bolts. I went to the local auto parts store and bought brand new bolts. Here's my advice, you should buy brand new bolts for your new water pump. The old bolts are old, beaten-up, stressed by hot-cold engine temperature and probably stretched out. The water pump uses five bolts, one of them is a little longer (about 1 3/4 inches long). I couldn't find 1 3/4 inches long bolt, so I had to use the old bolt. The other four bolts are 1 1/4 inches, they can be found at the auto parts store. I use Dorman brand 5/16"-18 x 1 1/4" Hex Head Cap Screws. You should also include 5/16" washers. I had to go real easy on an old bolt. The bolts should be tighted at 30 ft/lbs.
Hope it helps!
))- It sounds like you have air stuck in the heater core. Try elevating the front of your jeep and idling for a while with the radiator cap removed.
